1972 Clutch Cable - Assistance Needed

[EWPurdy]

After a 20 year hiatus from the 911 world, I'm back with a recently acquired 1972 911T.

The clutch feels pretty stiff compared to what I can recall so I've gone down the usual road of rebuilding the pedal cluster and am getting ready to replace the cable.

I took a look down at the transmission end of the cable and I see this:



I'm guessing that stack of washers is not what the Porsche engineers came up with so I'm wondering what everyone's thoughts are on that? The parts diagram does not show anything but a single nut for the 1972.



In general the pedal action is firm but smooth for about half the throw and then it gets very stiff and almost ratchety feeling. I thought it had to be the bushings but those are new now.

Thanks,
Eric

[proporsche]

you need this plastic spacer..91142321200 possibly your 911 is 1971..
https://www.pelicanparts.com/More_Info/91142321200.htm?pn=911-423-212-00-OEM&bc=c&q=91142321200

Ivan

[EWPurdy]

Thank you.

Definitely a 1972 as I have the external oil door specific to that year as well as the VIN beginning with 9112...the plot thickens. I'm beginning to think the stack of washers just prevents having to thread the nuts a few inches further down but serves no functional purpose with clutch operation.

[Jeff Higgins]

The throwout arm itself may be too far forward. Its right hand end, and the bottom of the pivot shaft over which it installs, are splined. There is a circlip keeping it from falling off the bottom. Remove that circlip, lower the arm off of the shaft, and re-clock it farther aft. Part of the increasing effort as the clutch disengages may be due to that arm going too far forward, which reduces leverage on it the more it points forward. Using a position of about 90 degrees across the car laterally as a reference, you want the arm to go about as far forward past 90 degrees at full release as it rests aft of 90 degrees at full engagement. Does that make sense? I feel like I may not be describing that all that well.

[EWPurdy]

That makes perfect sense!

[PeteKz]

Ditto what Jeff said. Make sure the arm is splined correctly.

[proporsche]

yes, my bad that plastic is for diferent clutch cable set up

Ivan

[EWPurdy]

Update: The image below shows the range of motion of the throw out lever. The factory manual says 79mm from the bell housing edge to the bottom of the cutout in the lever. Fumbling around with the micrometer it looks pretty close to that.



I swapped out the clutch cable and all the sticky motion is gone. I'm not sure how old it was but the difference in feel was immediate.

I will probably wait until I have the car back out on the road and see if the throw out lever needs to be resplined a notch or two. The feel is much better so I'm inclined to wait and see how it drives now.

On another front, how much "wiggle" is acceptable in the throw out lever? I imagine there are bushings in there that wear out as well.

[Jeff Higgins]

If that is the "at rest" position, with the clutch engaged, that is definitely too far forward. It should be about that far aft past 90 degrees when engaged, and about that far forward when released with the clutch pedal down.

Starting this far forward at rest will result in a pretty severe angel between the cable and the threaded end where the cable enters that threaded end, causing it to break prematurely.

[EWPurdy]

The "pedal up" position shown is at rest. I superimposed two images to draw that additional line on the one with the pedal fully depressed. Yes, it's definitely not symmetrical around a 90 degree angle to the case as you suggested.

I ordered a new metal clevis today as the one I have appears to be plastic. I'll get in there and re-index the lever when I replace the clevis.

Thanks for the advice.

-Eric

[EWPurdy]

I'm also going to see if I can accurately measure this distance to compare.

[PeteKz]

Originally Posted by Jeff Higgins

If that is the "at rest" position, with the clutch engaged, that is definitely too far forward. It should be about that far aft past 90 degrees when engaged, and about that far forward when released with the clutch pedal down.

Starting this far forward at rest will result in a pretty severe angel between the cable and the threaded end where the cable enters that threaded end, causing it to break prematurely.

Agree with Jeff again. On my mid-70's 915, the clutch release arm is about 90 degrees to the centerline of the transmission at rest. Yours is off by at least one tooth.

[Jeff Higgins]

Originally Posted by EWPurdy

I'm also going to see if I can accurately measure this distance to compare.

Great representation of the "released" position, with gravity holding it there. "Engaged" would be about that far above horizontal.

[EWPurdy]

I tried to upload this with Pelican but it kept failing. Here's the picture is worth a thousand words version with the ratcheting motion caused by an old clutch cable.


https://jumpshare.com/embed/Kicg10gF0fQS4b7rQMfB

[3rd_gear_Ted]

For my 3.6 conversion with Patrick flywheel & early clutch arm I used a thicker 930 type clutch cable. adjusting nut end is 11MM instead of 10MM
About 10 different GEMO cable lengths and thickness are available.

[Wangrande]

All good advice. The clutch fork internal against the throwout bearing is cast and will crack and fail. mine gave way over a few days and gave my feeble mind a workout because i had never encountered thr same in any other vehicle.

[EWPurdy]

I installed the metal clutch trunion today and played with the positions of the throw out arm. Moving the arm one notch as suggested resulted in the arm being at the very bitter end of the new clutch cable. There's perhaps 3-4 threads available on the cable in this position. That just looked wrong compared to all the images I've seen. I went back to the prior position since there was no notch in between. It looks very much like this image out of the owners manual in the original position. I'll reserve final judgement for after a test drive.

[Jeff Higgins]

There is significant adjustment available at the front of the clutch cable as well. You can screw the forward clevis out until the threads on the forward end of the cable are flush with the back of the clevis opening. I have seen that forward end of the cable screwed so far into the clevis that it fouls on the pivot arm, binding up the whole works and causing the cable to break where that threaded end is swagged onto it. Flush or even just below is plenty.